The first human trial of an artificial 'bio' kidney has shown encouraging results, offering hope of a working implant for patients, say US experts.
19,000 UK people receive dialysis
Ten kidney patients at the University of Michigan tested the device, which works in the same way as dialysis but is partly made of human cells.
Eventually, scientists hope the device will become an implantable long-term replacement for failing kidneys.
The results are published in the journal Kidney International.
The patients were all seriously ill with acute renal failure and other medical conditions.
Each received up to 24 hours treatment with the renal tubule assistant device (RAD).
The device is used outside the body and helps filter toxins from the blood.
It is made up of hollow fibres lined with the type of kidney cells that reabsorb vital electrolytes, water, and glucose filtered out of blood, in addition to producing other important molecules that the body needs to fight infection.
This makes it more similar to a real kidney than conventional dialysis machines.
In the study, six of the ten patients survived more than 30 days after the treatment with the RAD.
Several of the patients had to be taken off the treatment early because of reactions such as low blood sugar levels or because of complications related to their other medical conditions.
Professor David Humes, lead researcher, said their findings were very good when it was considered how poor the outcome usually is for patients that ill.
"It's a small study but it was compelling enough for us and the Food and Drug Administration to agree to go forward with a full phase II study," he said.
"The long-term goal, if this shows effectiveness in patients with end stage renal disease, is to build a fully implantable device."
He said his team was working with engineers to design such an implant.
Over 7,000 people in the UK die from kidney failure every year.
There are around 19,000 people receiving kidney dialysis.
There is a chronic shortage of kidney donors, making new options for treating people with kidney failure extremely important.
A spokesman for the National Kidney Research Fund said: "We are very encouraged that scientists are constantly looking for ways to overcome the organ shortage problem as there are currently some 6,400 people needing a kidney transplant in the UK.
"However, this form of alternative transplant treatment being proposed by the University of Michigan Health System is premature and a long way from being a readily available replacement to human donated organs for transplantation."